A study of the electrochemical oxidation of guaiacol

Y. Samet1, R. Abdelhedi1*, A Savall2

1 Laboratoire de Radio-analyse et d’Environnement

Ecole Nationale d’Ingénieurs de Sfax, BPW, 3038 Sfax, Tunisia

2 Laboratoire de Génie Chimique, CNRS, Université Paul Sabatier

118, route de Narbonne, 31062 Toulouse, France

* Corresponding author. E-mail : Ridha.Abdelhedi@enis.rnu.tn

Received : 18 December 2001; revised version accepted : 22 June 2002

Abstract

The electrochemical oxidation of guaiacol (2-methoxyphenol) on a treated disk of gold was studied by cyclic voltammetry. At low concentration, guaiacol undergoes one irreversible anodic peak . The current of this peak has a diffusional origin. For guaiacol concentrations higher than 4 . 10-2 mol dm-3, the voltammogram shows a post-peak. The effect of experimental data on the ratio of these two peaks was examined. The proposed mechanism is based on the hypothesis of two-electron oxidation of the guaiacol molecule, involving the intermediary of three phenoxonium cation mesomers. Quantitative importance of these cations is governed by their relative stability. Hydrolysis of these phenoxonium cations would lead to the formation of catechol, methoxyhydroquinone and 3-methoxycatechol. The preliminary results show that guaiacol is quantitatively oxidized by electrolysis on lead dioxide to produce by the intermediary of catechol, methoxyhydroquinone and 3-methoxycatechol, the formic, oxalic and maleic acids which degradation leads to carbon dioxide.

Keywords : Electrochemical oxidation; Gold electrode; Guaiacol; Lead dioxide electrode.

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